Functional component, structure for attaching functional component, and tire

ABSTRACT

A functional component capable of stably detecting information indicative of a usage state of a tire, including an electronic component capable of acquiring information on a tire is housed and which is attachable to an inner circumferential surface of the tire; a housing having a housing part in which the electronic component is housed and a bottom surface to be opposed to the inner circumferential surface of the tire; a strain detection means provided on the bottom surface and configured to detect strain of the tire; a support part extending from the bottom surface toward the inner circumferential surface of the tire and more protruding than a surface of the strain detection means; and an elastic part made of an elastomer having a rigidity smaller than that of a material forming the support part and interposed between the bottom surface and the inner circumferential surface of the tire.

TECHNICAL FIELD

The present invention relates to a functional component or the like thatcan be attached to a tire.

BACKGROUND ART

Conventionally, there has been known an attachment structure for fittinga functional component, which has an electronic component housed in acase (housing) for acquiring a use state of a tire, into a patchcomponent which is formed as one component by vulcanizing and moldingrubber in advance and which has been vulcanization-adhered to an innersurface of the tire, and attaching the functional component to the tire.The patch component is set to have a thickness and a shape so as to forma rubber layer of a predetermined thickness between the inner surface ofthe tire and the functional component to thereby prevent the functionalcomponent from falling off and to mitigate shock associated with therotation of the tire (Patent Document 1).

CITATION LISTT Patent Document

Patent Document 1: Japanese Unexamined Patent Application PublicationNo.

SUMMARY OF THE INVENTION Technical Problem

However, on the functional component, the centrifugal force due to thetire rotation acts and the functional component is pushed toward theinner circumferential surface of the tire. At this time, because therubber layer of the patch component deforms due to its elasticity, adistance and a position of the functional component relative to theinner surface of the tire change due to the rotation speed of the tire.Hence there is a problem that the accuracy of detection of informationindicative of the use state of the tire detected by the functionalcomponent does not become stable.Accordingly, the present invention aims at providing a functionalcomponent and the like that can stably detect the information indicativeof the use state of the tire. Solution to Problem

As a configuration of the functional component for solving theabove-mentioned problem, there is provided a functional component inwhich an electronic component capable of acquiring information on a tireis housed and which is attachable to an inner circumferential surface ofthe tire, the functional component including: a housing having a housingpart in which the electronic component is housed and a bottom surface tobe opposed to the inner circumferential surface of the tire; a straindetection means provided on the bottom surface and configured to detectstrain of the tire; a support part extending from the bottom surfacetoward the inner circumferential surface of the tire and more protrudingthan a surface of the strain detection means; and an elastic part madeof an elastomer having a rigidity smaller than that of a materialforming the support part and interposed between the bottom surface andthe inner circumferential surface of the tire..According to this configuration, by providing the support part on thebottom surface, even if the centrifugal force due to the tire rotationacts on the functional component, the support part supports thefunctional component, hence a distance between the inner surface of thetire and the strain detection means can be maintained constant, andvariation in the accuracy of detection (improvement of accuracy) by thestrain detection means can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams illustrating a functional componentattached on a tire.

FIG. 2 is a sectional view and a partially enlarged view of the functioncomponent.

FIG. 3 is a plan view of a housing.

FIG. 4 is a diagram illustrating a schematic configuration of a straindetection part.

FIGS. 5A and 5B are diagrams illustrating work process for attaching thefunctional component to the tire.

FIG. 6 is a diagram illustrating an adhesion process.

FIG. 7 is a diagram illustrating movement of the functional component.

Hereinafter, the present invention is described in detail through anembodiment of the invention, but the following embodiment is notintended to limit the invention set forth in the claims, and not allcombinations of features described in the embodiment are essential tothe solving means of the invention, and include selectively employedconfigurations.

DESCRIPTION OF EMBODIMENT

FIGS. 1A and 1B are diagrams illustrating an attachment state of afunctional component 1 attached to a tire 10. As illustrated in FIG. 1A,the tire 10 is assembled to a wheel rim 15, and an inner space of thetire 10 is filled with gas such as air.

As illustrated in FIGS. 1A and 1B, the functional component 1 is fixedby an adhesive agent to an inner surface (inner circumferential surface10 s) of the tire 10 and is disposed at the center CL in a widthdirection of the inner circumferential surface 10 s that is a back sideof a tread 11, which is to be in contact with a road surface, of thetire 10.

The functional component 1 has a housing (housing part) 2, a module 6and a covering member 8. The type of the tire 10 to which the functionalcomponent 1 is attached is not particularly limited, but mainly thefollowing tires are enumerated, which are: tires of automobilestraveling on ordinary paved roads (general roads and highways) such aspassenger cars, trucks, buses or the like; and tires of aircraft or thelike.

FIG. 2 is a sectional view and a partially enlarged view of the functioncomponent 1. FIG. 3 is a plan view of the housing 2.As illustrated in FIG. 2 and FIGS. 3A and 3B, the housing 2 includes acircular bottom part 21 and a peripheral wall part 22 rising from anouter peripheral edge of the bottom part 21 and is formed in a bottomedcylindrical shape with an opening on one side thereof, which forms ahousing space S (housing part) for housing the module 6 surrounded bythe bottom part 21 and the peripheral wall part 22. An innercircumferential surface 20 a of the peripheral wall part 22 forming thehousing space S is formed, for example, as a cylindrical tubular surfacehaving a constant diameter, and an inner bottom surface 20 c of thebottom part 21 is formed, for example, in a planar shape orthogonal tothe center axis O of the peripheral wall part 22 (inner circumferentialsurface 20 a). On the inner circumferential surface 20 a and the innerbottom surface 20 c, support means such as not-shown protrusions or thelike for supporting the module 6 are formed. The housing 2 is formed of,for example, synthetic resin or the like form the viewpoint of weightreduction and strength of the functional component 1. Incidentally, thematerial forming the housing 2 may be changed appropriately taking theabove-mentioned weight and the strength into consideration.In the following description, directions are specified as an axialdirection, a circumferential direction, a radial direction and the like,with the center axis O of the peripheral wall part 22 as a reference.

On the outer circumferential surface 20 b of the peripheral wall part22, plural annular convex parts 23 with concaves and convexes continuingalong the center axis O are formed. The annular convex part 23 isprovided on the lower side portion (bottom 21 side) of the peripheralwall part 22 and is formed in plural numbers (three in this example) atpredetermined intervals in the axial direction. Each of the annularconvex parts 23 extends along the circumferential direction of the outercircumferential surface 20 b around the center axis O over one round.The annular convex part 23 may be configured to extend intermittently inthe circumferential direction without extending over one round.

As illustrated in FIG. 2 and FIG. 3A, the outer bottom surface 20 d ofthe bottom part 21 is formed in a convex shape that bulges, at thecentral portion of the outer bottom surface 20 d, outwardly in the axialdirection (opposite side to the housing space S) than the outerperipheral edge side of the outer bottom surface 20 d. In thisembodiment, the outer bottom surface 20 d is formed in a spherical shapein which a center of curvature is provided on the center axis O and apredetermined radius of curvature is set. As illustrated in FIGS. 1A and1B, this outer bottom surface 20 d is the surface that faces the innercircumferential surface 10 s of the tire 10 when the functionalcomponent 1 is attached to the inner circumferential surface 10 s of thetire 10.

Incidentally, the bulging shape of the outer bottom surface 20 d is notlimited to the spherical shape. For example, it may be a polygonalpyramidal shape such as a circular cone or a square cone with theposition of the vertex set on the center axis O, or a pyramidaltrapezoid or the like, or any other curved shape formed by a part of anelliptic sphere. The outer bottom surface 20 d does not need to bebulged out over its entirety, but only portions in the vicinity of thecenter axis O may be partially bulged out in the curved shape asdescribed above. For example, in a case where the tire outer diameter islarge, the outer bottom surface 20 d may be formed in a flat shape.

The bottom part 21 is provided with a strain sensor attaching part 26which constitutes the module 6, a through hole 29 penetrating from theouter bottom surface 20 d to the inner bottom surface 20 c, and theplurality of convex parts 24 and the plurality of support parts 25protruding from the outer bottom surface 20 d.

The strain sensor attaching part 26 is provided on the outer bottomsurface 20 d as a one-way long concave part recessed in a flat plateshape that passes through the center axis O and extends along the radialdirection. The direction of extension of the strain sensor attachingpart 26 coincides with the direction of rotation of the tire 10. Thebottom surface recessed as the concave part is formed , for example, inthe planar shape parallel to the inner bottom surface 20 c. In thisstrain sensor attaching part 26, as illustrated in FIG. 2 , a basemember 28, which becomes a base for attaching the strain sensor 68, isprovided.

The base member 28 is formed, for example, in a planar shape whichconforms to the shape of the strain sensor attaching part 26 recessed atthe outer bottom surface 20 d and a part thereof is embedded. The basemember 28 is fixed to the strain sensor attaching part 26, for example,by an adhesive agent or the like. The base member 28 is formed, in thestate of being fixed to the strain sensor attaching part 26, in a planarshape of which exposed surface (strain sensor attaching surface)intersects orthogonally with the axial direction. The thickness of thebase member 28 is set so that, for example, the strain sensor attachingsurface is exposed from the outer bottom surface 20 d formed in thespherical shape at a position where the strain sensor attaching surfaceintersects the center axis O. With this, when the strain sensor 68 isattached to the base member 28, the strain sensor 68 is exposed from theouter bottom surface 20 d, thus the strain associated with the rotationof the tire 10 can be detected precisely. For the base member 28, anelastomer such as rubber is used, and in this embodiment, silicon rubberwith a Shore A hardness of about 50 was used.

As illustrated in FIGS. 2 and 3 , (3A and 3B) the through hoke 29 isprovided adjacent to one end side of the strain sensor attaching part26. The through hole 29 extends along the axial direction from the innerbottom surface 20 c to the outer bottom surface 20 d of the housing 2,and is provided as a through hole penetrating through the bottom part21. The through hole 29 is formed, for example, to be a rectangularshape in a cross-sectional view orthogonal to the direction ofextension. In the through hole 29, wiring 88 extending from the strainsensor 68 provided to be exposed to the outside of the housing 2 isinserted.

As illustrated in FIG. 3B, the convex part 24 and the support part 25are provided on the outer bottom surface 20 d of the bottom part 21, insuch a manner as to avoid the above-mentioned strain sensor attachingpart 26 and the through hole 29. The convex parts 24 are selectivelyprovided, while avoiding the strain sensor attaching part 26 and throughhole 29, for example, at positions where two concentric circles Cl andC2, which have different diameters and which are centered at the centeraxis O penetrating the outer bottom surface 20 d, intersect with aplurality of straight lines L1 to L4 which pass the center axis O andwhich are set at equal intervals in the circumferential direction. Thepositions where the convex parts 24 are formed are not limited to theabove-mentioned positions and may suitably be set, however, it ispreferable to form them in a symmetry pattern such as a point symmetryaround the center axis O, or a line symmetry with respect to thestraight line L3 (the direction of extension of the strain sensorattaching part 26) in FIG. 3B.

The convex parts 24 are formed in a cylindrical shape protruding in anormal direction of the outer bottom surface 20 d at the respectivepositions. The tip end of the convex part 24 is formed in a planar shapeorthogonal to the direction (normal direction of the outer bottomsurface 20 d) in which the convex part 24 protrudes. The length of theconvex part 24 extending from the outer bottom surface 20 d is describedbelow.Incidentally, the shape of the tip end is not limited to the planarshape, but may be a spherical shape. Further, the shape of the convexpart 24 is not limited to the cylindrical shape, but may be a polygonalpillar, a cone or the like. Furthermore, instead of the convex part 24protruding from the outer bottom surface 20 d, a concave part, like adimple of a golf ball, recessing from the outer bottom surface 20 dtoward the inner bottom surface 20 c may be provided. The convexity 24protruding from the outer bottom 20 d may be replaced by a concaveportion that depresses from the outer bottom 20 d toward the innerbottom 20 c, like a dimple on a golf ball.

As illustrated in FIG. 3B, the support part 25 is provided in pluralnumbers around the strain sensor attaching part 26. In this embodiment,the support parts 25 were formed at four positions of intersectionswhere the straight lines L2 and L4 intersect with the circle C1 that wasused to form the convex part 24. That is, as illustrated in FIG. 3B, thesupport parts 25 are so provided that, when planarly viewing the outerbottom surface 20 d, the end of the strain sensor attaching part 26 inthe extension direction exceed the rectangular-shaped area enclosed byfour support parts 25. The support parts 25 are formed in the same shapeat each position, for example, in the columnar shape extending from thebottom surface 20 d along the axial direction. The support part 25 isset to be larger in diameter than the diameter of the convex part 24.The tip end of each support part 25 is formed in a planar shapeintersecting orthogonally with the direction of extension of the supportpart 25.

The extension length of each support part 25 is so set that, when thestrain sensor 68 is attached to the housing 2, the tip end of thesupport part 25 protrudes more than the surface of the strain sensor 68.That is, as illustrated in FIGS. 1A and 1B, the length of the supportpart 25 is set so that, when the functional component 1 is attached tothe tire 10, the tip end of the support part 25 comes most proximate tothe tire inner circumferential surface 10 s.

As illustrated in FIG. 2 , the module 6 includes a circuit board 60 onwhich electronic components are mounted or connected, and a battery 70,and is configured to be able to be housed in the housing space S of thehousing 2 described above.

As illustrated in FIG. 2A, the circuit board 60 is provided with aplurality of sensors, for example such as a temperature sensor, apressure sensor, an acceleration sensor and a strain sensor 68 or thelike that function as a state acquisition means for acquiring a state inthe tire 10, a control means that controls the operation of these pluralsensors and the operation of the transmission means and includes amemory means that store the history of detected values detected by eachsensor, an electronic component that functions as a not-showntransmission means or the like for outputting the detected valuedetected by each sensor to the outside of the tire, and metal terminals69A and 69 B that supply the power from the battery 70 to thesecomponents. Incidentally, the configuration of the circuit board 60 isnot limited to this.

The temperature sensor, the pressure sensor and the acceleration sensorare mounted on the circuit board 60, and the strain sensor 68 isconnected to the circuit board 60 via the wiring 88.The control means is configured, for example, as a one-chip IC or thelike those functions as a so-called computer and is mounted on thecircuit board 60. The control means is provided with a CPU as acomputing means provided as a hardware resource, a ROM and a RAM as thememory means, and an input/output interface as an external device, andother components.

The control means executes a predetermined program upon detection of,for example, the rotation (centrifugal force) of the tire 10 by theacceleration sensor, stores a temperature, a pressure, an accelerationand a strain in the tire 10, which were detected by the temperaturesensor, the pressure sensor, the acceleration sensor and the trainsensor 68, respectively, in the memory means as a history, and outputsthem to the transmission means via the input/output interface. Thetemperature, the pressure, the acceleration and the strain outputted tothe transmission means are then outputted via the transmission means to,for example, a vehicle body unit provided in a vehicle.

The transmission means is mounted on the circuit board as a transmissioncircuit and transmits the temperature, the pressure and theacceleration, which have been measured, to the outside of the tire via anot-shown antenna. Signals such as the temperature, the pressure, theacceleration and the strain transmitted wirelessly from the transmittingmeans are received, for example, by a wireless circuit of the main unitprovided in a not-shown vehicle, and information on the tire state(temperature, pressure, or presence or absence of abnormality) isdisplayed on ta display unit provided inside the vehicle.

The battery 70 is a so-called disk-shaped button battery, which isconnected to the circuit board 60 as each electrode thereof issandwiched between the metal terminals 69A; 69B provided on the circuitboard 60, and supplies the power to each sensor, the control means, thetransmitting means and other components. The battery 70 is not limitedto the button battery, but may be a cylindrical battery, and its form isnot particularly limited.

The acceleration sensor 66 is a sensor that can measure accelerations inthree axial directions, for example, the tire width direction, theradial direction and the circumferential direction (tangential directionof rotation), and is attached so that each measurement direction isturned in a predetermined direction with respect to the circuit board60. It is preferable that the acceleration sensor 66 be attached on thecircuit board 60 in such a manner that, when attached to the tire 10 asthe functional component 1, the acceleration sensor 66 is positioned atthe center in the tire width direction. In addition, not-shownpositioning means, which are fitted to each other, are provided on thecircuit board 60 and in the housing 2. With this, a measurementdirection of the acceleration sensor 66 with respect to the housing 2 isdefined.

As illustrated in FIG. 2A, the strain sensor 68 is provided with asensitive strip 68A and a strain detection part 68B. The sensitive strip68A is formed of a thin metal plate having an elasticity, for example,and is provided on the base member 28.The sensitive strip 68A is positioned, for example, as one end sidethereof is extended into the housing space S via the through hole 29 andlocked by a not-shown locking means provided in the housing 2.

The strain detection part 68B is attached on an outer surface of thesensitive strip 68A so as to be positioned on the center axis O, anddetects a strain of the tire 10 occurring when the tire 10 steps in orkicks out, through deformation of the sensitive strip 68A associatedwith the rotation of the tire 10. The strain detection part 68B may bepositioned at a position on the center axis O, which is the closestposition relative to the inner circumferential surface 10 s of the tire10.

FIG. 4 is a diagram illustrating a schematic configuration of the straindetection part 68B. As illustrated in FIG. 4 , the strain detection part68B is provided with, for example, a strain gage 80, a bridge circuit82, a strain amplifier 84 and so on. The strain gage 80 constitutes partof the bridge circuit 82. To the bridge circuit 82, for example, avoltage is applied from the strain amplifier 84, and the bridge circuit82 outputs, as a signal, a voltage difference associated with a changein the resistance value of the time when the strain gage 80 detected astrain.

The strain amplifier 84 is provided with a signal amplifying circuit, anA/D converter and a power supply part. The strain amplifier 84 amplifiesthe signal inputted from the bridge circuit 82 by the signal amplifyingcircuit, converts the amplified signal into a digital signal by the A/Dconverter, and outputs the digital signal to the circuit board 60. Inother words, a voltage value corresponding to a strain amount detectedby the strain gage 80 is outputted, as the digital signal, by the strainamplifier 84 to the circuit board 60.The strain sensor 68 is connected to the circuit board 60 by the wiring88 passing through the through hole 29 provided in the bottom part 21 ofthe housing 20.

In this embodiment, for the strain detection part 68B, a sensor chip wasapplied, in which functions of the strain gage 80, of the bridge circuit82 and of the strain amplifier 84 were integrated into one chip forexample, and which was configured as a so-called piezo resistancesemiconductor. With the strain detection part 68B, for example, ameasurement surface 68 a is defined and the strain detection part 68B isattached so that the measurement surface 68 a is opposed to the surfaceof the sensitive strip 68A. In this way, by detecting via the sensitivestrip 68A, as the strain, the deformation of the tire 10 by the strainsensor 68 configured by the semiconductor, it is possible to improve thereliability of measurements and durability, to reduce the power consumedfor detection of the deformation of the tire 10, and to share the powerwith electronic components such as other sensors.

The module 6 configured as described above is positioned and housed insuch a manner that the battery 70 is attached to the circuit board 60and disposed to be opposed to the inner bottom surface 20 c of thehousing space S, and the direction of measurement by the accelerationsensor mounted on the circuit board 60 is turned in a predetermineddirection with respect to the housing 2.

As illustrated in FIG. 2 , the functional component 1 is integrallycovered by the covering member 8 in a state where the module 6 is housedin the housing space S of the housing 2. The covering member 8 is moldedso as to cover the entire outside of the housing 2 while being filled inthe housing space S by molding, for example. For the covering member 8,an elastomer such rubber and the like having rigidity lower than that ofthe support part 25 is used. As the elastomer, it is preferable that itcan follow the deformation caused in association with the rotation ofthe tire 10 when the portion where the functional component 1 isattached was brought into contact with the ground.

The covering member 8 after having been molded is provided with anelastic part which is interposed between the outer bottom surface 20 dand the inner circumferential surface 10 s, when the functionalcomponent 1 is attached to the inner circumferential surface 10 s of thetire 10. On this elastic part, the adhesion surface 8 z to be adhered tothe inner circumferential surface 10 s of the tire 10 is molded. Theadhesion surface 8 z is formed in planer shape which intersectsorthogonally with the center axis O. In this embodiment, the adhesionsurface 8 z is formed so as to be flush with the tip end surfaces 25 tof the plurality of support parts 25. In the covering member 8, acommunication hole is provided, which enables the temperature sensor andthe pressure sensor to contact with air in the tire 10.

The covering member 8 is filled, by molding, into the housing space S ofthe housing 2 in which the module 6 has been housed, covers the outerperiphery of the peripheral wall part 22 of the housing 2 while coveringthe opening part of the housing 2, covers the outer periphery of theperipheral wall part 22 so as to be fan-shaped toward the outer bottomsurface 20 d of the housing 2, and molded into a truncated cone shapehaving a planar part that intersects orthogonally with the center axisO. This planar part functions as the adhesion surface 8 z to be adheredto the tire 10. In this embodiment, the adhesion surface 8 z is moldedto be flush with the tip end part 25 t of the support part 25, forexample.

On the outer surface of the covering member 8, as illustrated in FIG.1B, attachment marks M indicating the attachment direction are molded atthe time of the molding. The attachment marks M are formed as a Δ markM1 indicating a front side and a mark M2 indicating a rear side in thedirection of rotation, and two ○ marks M3; M3 indicating the tire widthdirection. The mark M1 corresponds to the tip end side of the sensitivestrip 68A exposed from the housing 2, and the mark M2 is formed tocorrespond to the rear end side.

As illustrated in the enlarged view of FIG. , 2 , a relationship of thesupport part 25, the strain sensor 68 and the convex part 24, is so setthat the tip end (tip end surface 25 t) of the support part 25, thesurface 68 z of the strain sensor 68 and the tip end 24 z of the convexpart 24 become sequentially lower in this order. The lengths, extendingfrom the outer bottom surface 20 d, of the support part 25 and theconvex part 24 may be set so as to satisfy the above-mentionedrelationship, with the thickness of the strain sensor 68 as a reference.

In this way, by making the covering member 8 as a filler to be filled inthe housing space S and integrally molding with the housing 2 to protectthe housing 2, the manufacturing process can be simplified. In addition,since the housing 2 is provided with the plurality of annular convexparts 23 on the outside of the peripheral wall part 22 and the pluralityof convex parts 24 on the outer bottom surface 20 d of the bottom part21, the positional displacement relative to the covering member 8 isprevented, hence even when external force is applied to the functionalcomponent 1 in association with the rotation of the tire 10, the housing2 and the covering member 8 can be integrated.

FIGS. 5A and 5B are diagrams illustrating work process for attaching thefunctional component 1 to the tire 10.The functional component 1 formed as described above is adhered to theinner circumferential surface 10 s of the tire 10 by means of anadhesive agent, such as an instantaneous adhesive agent, that forms athin film layer on the adhesion surface 8 z after having been adhered.The process of adhering the functional component 1 to the tire 10 isdescribed below.As illustrated in FIG. 5A, the process of attaching the functionalcomponent 1 to the tire 10 is largely divided into a process ofpretreating the tire 10 (tire pretreatment process) and an adhesionprocess.

As illustrated in FIG. 5B, the tire pretreatment process includes a moldrelease agent removal process, a ridge treatment process and a cleaningprocess. The mold release agent removal process is a process forremoving a mold release agent adhered to the inner circumferentialsurface of the tire after vulcanization-molding, in which, for example,a spray-type degreasing agent is sprayed on ta predetermined position ofthe inner circumferential surface 10 s of the tire 10 and the moldrelease agent is wiped off.

The ridge treatment process is a process for adjusting (flattening) theridge (convex part) formed on the inner circumferential surface 10 s ofthe tire 10 by a bladder in the vulcanization-molding process to thesurrounding level, for example, polishing by buffing or the like using arotary tool such as a leutor. Incidentally, in a case where this processcannot be performed, this process may be omitted. In the cleaningprocess, cleaning spray is applied to remove buffing grouts and thelike, and thereafter, drying using a dryer or the like.

As illustrated in FIG. 6 , in the adhesion process, the adhesive agentis applied to the entire adhesion surface 8 z and the functionalcomponent 1 is pressed with a predetermined force and adhered to theinner circumferential surface 10 s of the tire 10. For the adhesiveagent, for example, an instantaneous adhesive agent or the like can beused, and it is preferable to use an adhesive agent having elasticityafter cured (adhered). It is more preferable to use an adhesive agentthat makes a thin adhesion layer to be formed between the adhesionsurface 8 z and the inner circumferential surface 10 s.

FIG. 7 is a diagram illustrating movement of the functional component.As illustrated in FIG. 7 , because the support part 25 is in contactwith the inner circumferential surface 10 s of the tire 10 even thoughthe centrifugal force P associated with the rotation of the tire 10 actsthe functional component 1, the position of the functional component 1relative to the inner circumferential surface 10s of the tire 10 doesnot change.In other words, even in cases where the functional component 1 is in astep-in position p1 in the rotation of the tire 10, in a ground contactposition p2 and in a kick-out position p3, the tip ends of the foursupport parts 25 provided in the housing 2 are constantly in contactwith the inner circumferential surface 10 s, thus the distance betweeneach sensor provided in the housing 2 and the inner circumferentialsurface 10 s is maintained constant. Accordingly, even though thecentrifugal force P acting on the functional component 1 changesresulting from the change in the rotational speed of the tire 10, stablemeasurement can be performed and accuracy of the detection of the usestate of the tire can be improved.

In addition, as the tip end of the strain sensor 68 is more protrudingin the rotational direction of the tire 10 than the support part 25, thedeformation of the tire 10 when reaching the step-in position p1 forexample, is transmitted through the covering member 8. Thus, theaccuracy of detection of the deformation of the tire 10 can be improved.Accordingly, the closer the position where the support part 25 isdisposed to the strain detection part 68B of the strain sensor 68 is,the faster the deformation of the tire 10 associated with step-in can bedetected, and the longer the deformation of the tire 10 associated withkick-out can be detected.

In this way, taking the action of the support part 25 intoconsideration, the number of the support part 25 is not limited to four.Preferably, they may be provided in the same number sandwiching thestrain sensor 68, and more preferably, they may be provided to besymmetrical sandwiching the strain sensor 68. In other words, as theleast number of the support part 25, it may be provided to sandwich thestrain sensor 68 in between two support parts 25. In this case, asdescribed above, by disposing the support parts in the vicinity of thestrain detection part 68B provided at the center of the sensitive strip68A, the deformation of the tire 10 can be detected accurately.Furthermore, in a case where the strain sensor 68 is disposed betweenthe support parts 25 so as to be sandwiched, each support part 25 may bedisposed in the vicinity of the strain sensor 68. By providing thesupport part 25 in this manner, the deformation of the tire 10 can bedetected stably.

In the above-described embodiment, the explanation has been given in away that the elastic part interposed between the housing 2 and the innercircumferential surface 10 s of the tire 10 is integrally formed as thecovering member 8 that covers the entire housing 2. However, it is notlimited to this, and a range of covering the housing 2 may be suitablyset. For example, by forming the covering member 8 in the range coveringfrom the outer bottom surface of the housing 2 to the annular convexpart 23, as described above, by virtue of the action of the pluralconvex parts 24 and the annular convex parts of the housing 2, thedisplacement between the covering member 8 and the housing 2 can beprevented. In this case, the housing space S of the housing 2 in whichthe module 6 was housed may be filled with a so-called potting materialto fix the module 6 to the housing 2.

In the above-described embodiment, the explanation has been given in away that the tip end surface 25 t of the support part 25 is made flushwith the adhesion surface 8 z, that is, the tip end surface 25 t isexposed to the adhesion surface 8 z, but it is not limited to this. Forexample, the molding may be done to cover by the covering member 8 sothat the tip end surface 25 t is not exposed. In this case, needless tosay that, in the molding of the covering member 8, it is preferable toset the thickness between the adhesion surface 8 z and the tip endsurface 25 t to be thin.

REFERENCE SIGN LIST

1: Functional component, 2: Housing, 6: Module, 8: Covering member, 8 z:Adhesion surface, 10: Tire, 10 s: (Tire) inner circumferential surface,20 a: Inner circumferential surface, 20 b: Outer circumferentialsurface, 20 c: Inner bottom surface, 20 d: Outer bottom surface, 21:Bottom part, 22: Peripheral wall part, 23: Annular convex part, 24:Convex part, 24 z: Tip end, 25: Support part, 25 t: Tip end surface, 26:Strain sensor attachment part, 28: Base member, 29: Through hole, 60:Circuit board, 68: Strain sensor, 68A: Sensitive strip, 68B: Straindetection part, 68 z: Surface, S: Housing space.

1. A functional component in which an electronic component capable ofacquiring information on a tire is housed and which is attachable to aninner circumferential surface of the tire, the functional componentcomprising: a housing having a housing part in which the electroniccomponent is housed and a bottom surface to be opposed to the innercircumferential surface of the tire; a strain detection means providedon the bottom surface and configured to detect strain of the tire; asupport part extending from the bottom surface toward the innercircumferential surface of the tire and more protruding than a surfaceof the strain detection means; and an elastic part made of an elastomerhaving a rigidity smaller than that of a material forming the supportpart and interposed between the bottom surface and the innercircumferential surface of the tire.
 2. The functional componentaccording to claim 1, wherein the support part is provided in pluralnumbers.
 3. The functional component according to claim 2, wherein thestrain detection means is disposed among the plurality of support parts.4. The functional component according to claims 1, wherein thefunctional component comprises a convex part which protrudes from thebottom surface toward the inner circumferential surface of the tire anda tip end thereof is positioned more on a side of the bottom surfacethan a tip end of the support part.
 5. The functional componentaccording to claims 2, wherein the functional component comprises aconvex part which protrudes from the bottom surface toward the innercircumferential surface of the tire and a tip end thereof is positionedmore on a side of the bottom surface than a tip end of the support part.6. The functional component according to claims 3, wherein thefunctional component comprises a convex part which protrudes from thebottom surface toward the inner circumferential surface of the tire anda tip end thereof is positioned more on a side of the bottom surfacethan a tip end of the support part.
 7. The functional componentaccording to claim 1, wherein the tip end of the support part is exposedfrom the elastic part.
 8. The functional component according to claim 2,wherein the tip end of the support part is exposed from the elasticpart.
 9. The functional component according to claim 3, wherein the tipend of the support part is exposed from the elastic part.
 10. Thefunctional component according to claim 4, wherein the tip end of thesupport part is exposed from the elastic part.
 11. A structure forattaching the functional component according to claim 1 to a tire,wherein a tip end surface of the support part and the elastic part areattached to the inner circumferential surface of the tire via anadhesive agent.
 12. A structure for attaching the functional componentaccording to claim 2 to a tire, wherein a tip end surface of the supportpart and the elastic part are attached to the inner circumferentialsurface of the tire via an adhesive agent.
 13. A structure for attachingthe functional component according to claim 3 to a tire, whereina tipend surface of the support part and the elastic part are attached to theinner circumferential surface of the tire via an adhesive agent.
 14. Astructure for attaching the functional component according to claim 4 toa tire, wherein a tip end surface of the support part and the elasticpart are attached to the inner circumferential surface of the tire viaan adhesive agent.
 15. A structure for attaching the functionalcomponent according to claim 5 to a tire, wherein a tip end surface ofthe support part and the elastic part are attached to the innercircumferential surface of the tire via an adhesive agent.
 16. Astructure for attaching the functional component according to claim 6 toa tire, wherein a tip end surface of the support part and the elasticpart are attached to the inner circumferential surface of the tire viaan adhesive agent.
 17. A structure for attaching the functionalcomponent according to claim 7 to a tire, wherein a tip end surface ofthe support part and the elastic part are attached to the innercircumferential surface of the tire via an adhesive agent.
 18. Astructure for attaching the functional component according to claim 8 toa tire, wherein a tip end surface of the support part and the elasticpart are attached to the inner circumferential surface of the tire viaan adhesive agent.
 19. A structure for attaching the functionalcomponent according to claim 9 to a tire, wherein a tip end surface ofthe support part and the elastic part are attached to the innercircumferential surface of the tire via an adhesive agent.
 20. Astructure for attaching the functional component according to claim 10to a tire, wherein a tip end surface of the support part and the elasticpart are attached to the inner circumferential surface of the tire viaan adhesive agent.